CN111360196A

CN111360196A - Method for improving fluidity of cast magnesium alloy in casting mold

Info

Publication number: CN111360196A
Application number: CN202010274470.2A
Authority: CN
Inventors: 陈加运; 何凯; 秦守益; 张娜; 张旭亮; 王小冬; 曾柏栋
Original assignee: Shanghai Space Precision Machinery Research Institute
Current assignee: Xinjiang Technology (Jiangsu) Co.,Ltd.
Priority date: 2020-04-09
Filing date: 2020-04-09
Publication date: 2020-07-03
Anticipated expiration: 2040-04-09
Also published as: CN111360196B

Abstract

The invention relates to a method for improving the fluidity of a cast magnesium alloy melt in a casting mold. The method specifically comprises the following steps: spraying sodium alkyl sulfonate aqueous solution on the surface of a casting mold or a loam core, drying, coating water glass, igniting an organic matter with high carbon content, and then smoking and roasting the organic matter with flame aiming at the surface of the casting mold to ensure that carbon particles generated by incomplete combustion of the organic matter are uniformly adhered to the surface of the core contacted with molten metal, so that the roughness of the surface of the casting mold is reduced, and the fluidity of the molten metal in the casting mold is improved. The method can improve the fluidity of the cast magnesium alloy in the casting mould, so that the capability of forming a complex thin-wall casting is enhanced; meanwhile, the fluidity of the metal liquid is increased, so that the alloy pouring temperature is reduced under the same casting mold condition, thereby reducing the defects of looseness and the like.

Description

Method for improving fluidity of cast magnesium alloy in casting mold

Technical Field

The invention relates to a casting method of an alloy casting, in particular to a method for improving the fluidity of an alloy in a casting mold.

Background

In the fields of aerospace, automobiles and the like, the weight reduction of the product can increase the load of the system and save more energy on the premise of meeting the use performance. The magnesium alloy has the advantages of low density, high specific strength, excellent processing performance and the like, so the magnesium alloy is more and more widely applied. The continuous development of the industry needs various magnesium alloy castings with excellent performance and complex structure to meet various use requirements.

In the casting process, the alloy liquid is firstly filled into a casting mold and then solidified to form a casting, and if the casting mold cannot be filled with the metal liquid, the defects of cold shut, insufficient casting and the like can be caused, and the casting is scrapped. In the mold filling process, on one hand, molten metal wets the casting mold, so that the flow is subjected to resistance, and the fluidity of the molten metal is poor; on the other hand, molds such as sand molds and metal molds have a cooling effect on molten metal, and the lower the temperature, the poorer the fluidity of the molten metal. At present, when a casting with a complex structure and high requirement on internal quality is poured, the situation of insufficient cast-in-place of a thin-wall part often occurs; if the pouring temperature is increased, the casting defects such as shrinkage cavities, looseness and the like often occur at other parts. In casting production, liquid coating is often used on the surface of a casting mold to ensure the surface smoothness, so that the fluidity of molten metal is increased. However, the magnesium alloy has extremely active chemical properties, the conventional coating is easy to react with the magnesium alloy to cause quality and potential safety hazards, and the flame retardant in the flame-retardant coating is decomposed at high temperature to influence the quality of castings, so that some castings with higher quality requirements are defective or scrapped.

The method not only effectively improves the flowing capability of the molten metal in the casting mold, but also does not cause negative reaction between the molten metal and the surface substance of the mold core, and has important significance for ensuring the product quality.

Disclosure of Invention

The technical problem solved by the invention is as follows: aiming at the problems that alloy liquid at a thin-wall part is difficult to fill and the conventional coating has potential quality hazards in the forming process of a complex magnesium alloy casting, the method for improving the fluidity of the cast magnesium alloy in a casting mold is disclosed, and the purpose of improving the fluidity of the metal liquid in the casting mold is achieved.

The technical scheme of the invention is as follows: a method for improving the fluidity of a cast magnesium alloy melt in a casting mold comprises the following steps:

1) spraying a layer of sodium alkyl sulfonate aqueous solution on the surface of a magnesium alloy casting or a loam core;

2) after drying the loam core or the casting mold, coating a layer of water glass on the surface of the loam core or the casting mold;

3) igniting the carbon-containing organic matters to continuously combust;

4) black smoke generated by burning the carbon-containing organic matter is directed at the surface of the magnesium alloy casting or the loam core for smoking;

5) after the surface of the casting mould or the sand core is completely blackened and coated with a layer of carbon particles, the surface roughness of the sand mould is reduced, and the fluidity of the molten metal in the sand mould is improved.

The concentration of the sodium playylsulfonate aqueous solution is 15% -25%.

The organic matter is high carbon content organic matter and can be incompletely combusted in the air to generate black smoke.

The coated carbon layer is about 0.5-1.2 mm.

The invention has the following beneficial effects:

1. the carbon element has inactive chemical property and can not react with molten metal, so the method can not generate negative influence on the quality of the magnesium alloy casting.

2. The carbon generated by combustion has low granularity, is fine and smooth, can effectively improve the surface smoothness of the casting mould, and improves the surface quality of the casting.

3. The carbon particles generated by combustion and the surface of the core pretreated by the method have strong adhesive force, and the complex casting cavity is more convenient to treat.

4. The magnesium alloy is sensitive to water vapor, the water vapor content in the casting core needs to be controlled in the production process, and the casting mold is heated and baked in the carbon element coating process by the method, so that a large amount of water vapor in the casting mold is removed, and the quality of the casting is ensured.

Drawings

FIG. 1 is a schematic view of a hand-held acetylene combustion smoking.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, a detailed description of the present invention is provided below with reference to fig. 1.

In the following description, specific methods and details of core-smoke carbon coating using a hand-held acetylene torch are set forth to provide a thorough understanding of the present invention. The invention may be practiced in a variety of ways other than those described herein, such as: besides acetylene, the ignited organic matters can generate black smoke, namely carbon particles; the mold surfaces of the metal mold may also be coated with carbon in this manner, and so forth. The technical personnel can make popularization and improvement without departing from the content of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

Firstly, the method comprises the following steps: uniformly spraying a layer of sodium alkyl sulfonate aqueous solution with the concentration of 20 percent on the molded clay sand core 9, and heating and drying;

secondly, stably placing the clay sand core 9 on a sand mold lower box 10, and coating a layer of water glass solution on the surface of the clay sand core;

thirdly, the method comprises the following steps: the acetylene cylinder 1 is placed stably, and whether the ventilation switch 2, the flow display instrument 3, the flow control valve 4, the ventilation pipe 5, the handheld handle 6 and the spray head 7 are damaged or not is checked.

Fourthly, the method comprises the following steps: then the flow control valve 4 is adjusted to the required state, the ventilation switch 2 is opened, and the acetylene is ignited by open fire after being sprayed.

Fifthly: the handhold handle 6 is held by hand, so that the black smoke 8 emitted from the front end of the ignited flame is directed at the clay sand core 9 for smoking.

Sixthly, the method comprises the following steps: and after the surface of the clay sand core 9 turns black, namely the surface is uniformly coated with 0.5-1.2mm carbon, closing the ventilation switch 2, closing the flow control valve 4, collecting the acetylene cylinder 1 and the like, and after the surface treatment is finished, continuously closing the box for pouring.

Claims

1. A method for improving the fluidity of a cast magnesium alloy melt in a casting mold is characterized by comprising the following steps:

3) igniting the carbon-containing organic matters to continuously combust;

2. The method of claim 1, wherein the step of increasing the fluidity of the cast magnesium alloy melt in the mold comprises: the concentration of the sodium playylsulfonate aqueous solution is 15% -25%.

3. The method of claim 1, wherein the step of increasing the fluidity of the cast magnesium alloy melt in the mold comprises: the organic matter is high carbon content organic matter and can be incompletely combusted in the air to generate black smoke.

4. The method of claim 1, wherein the step of increasing the fluidity of the cast magnesium alloy melt in the mold comprises: the coated carbon layer is about 0.5-1.2 mm.